Before we go there, let’s
take a look at our ribosomes.
Ribosome structure, we have reviewed
in our lecture on cell structures,
but we’ll go over some of that again.
There are small and large subunits.
The small subunit is generally involved
in the decoding of the messenger RNA,
sort of reading what’s on there.
There’s lots of protein and
lots of RNA in our ribosomes.
The large subunit, having lots of RNA,
is also involved in peptide bond formation
of the growing amino acid chain.
And I’ll show you how that
works coming up here shortly.
That large subunit contains the
enzyme peptidyl transferase,
which transfers peptides, so
that’s a hint of what’s coming up.
So the ribosome is a little bit
different than polymerases.
I had mentioned before that
the 5’ end is the front end
with the 5’ cap on the
mRNA’s head, right?
And that is the end that the
ribosome begins reading at.
So the ribosome will read from 5’ to
3’ in translating the messenger RNA
into a polypeptide chain.
So there are three sites on our ribosome.
and the E-site.
I named these the arrival site, the
polypeptide site and the exit site.
So A, P, and E.
It also spells APE, but I like to
remember them based on their functions.